Fire alarm



Patented July 21, 1936 UNITED STATES PATENT OFFICE FIRE ALARM George Howlett Davis, West Orange, N. J.

Application April 24, 1931, Serial No. 532,533

17 Claims.

My present invention relates generally to electrical fire-alarm and annunciator devices, and more specically to a unitary device of that type complete in itself and adapted to be plugged into,

and operated from the terminal socket of a standard commercial lighting system employing alternate currents or voltages ranging from 110 to 120, and this application is a continuation in part of my co-pending application, Serial Number 509,-

802, led January 19th, 1931.

The prime object of the invention is to provide a simple and compact signalling unit, having a terminal socket or plug of insulating material that may be cooperatively associated with the l5 wellknown socket or terminal member of existing standard electric lighting systems now generally in use, and wherein the sounding mechanism of the device is attached to and wholly carried by the plug terminal having the usual two contacts,

2o whereby the device may be manufactured and sold as a unit complete in itself for inter-changeable engagement at will with existing socket terminals.

A further object of the invention is to provide a signalling unit of the character stated that will be simple in construction, the parts of which may be easily and quickly assembled, and the cost of manufacture of which will be relatively low.

Briefly and generally stated, the invention comprises a fire-alarm unit adapted to be plugged into the socket terminal of a standard lighting system, comprising a plug of insulating material having two terminal contacts and an alarm mechanisrn carried thereby, said mechanism including an electro-magnet supported from the terminal plug, a vibratory diaphragm having a portion thereof overlying the pole of the magnet, a thermostatic switch, and means connecting one plug contact, the electro-magnet, the thermostatic switch and the other plug contact in series circuit, the said elements being co-operatively associated in a unitary structure complete in itself to be sold as a complete article of manufacture.

4l The invention is shown by way of illustration in the accompanying drawing, wherein:

Figure 1 is a central sectional view of the apparatus, and;

Figure 2, a top plan view thereof partly broken away. y

Referring to the construction in further detail, the apparatus consists of a two-piece plug or body portion 3 and 4 constructed to be assembled in the manner shown and securely connected to- 66 gether by the bolt 5, and a cap 6 overlies the plug and is constructed to provide screw-threads for fitting in the usual standard electric socket. A portion of the cap 6 is formed with a detent I adapted to engage a complementary notch in the plug member 3 for securely holding the cap as 5 shown, and the nut 3 of bolt, 5 closely fits within a recess in said plug member, Through the bolt 5 and nut 3 said parts 3 and 4 may be readily assembled or disassembled.

The plug member 3 has an enlarged annular 10 portion 9 of appreciable dimensions forming a central chamber or recess and adjacent which the alarm mechanism per se is suitably mounted. In this connection it will be noted the present disclosure marks a decided improvement over the 15 corresponding elements shown in my co-pending patent application above referred to, in that there are here employed fewer parts serving the same purpose, and assembled in a more compact and unitary structure. 20

The alarm element supporting device consists of a yoke member III secured to the body portion 9 by two bolts II that freely pass through openings formed in said body portion as shown. Said bolts have screw-threaded connection with the 25 yoke member I0 and the bolt heads I2 are countersunk in the plug element 9. A suitable insulating ring or plate I3 is interposed between the yoke member I0 and the plug part 9.

An electro-magnet I4 is secured to said yoke 30 II) by the nut bolt elements I5 and I6 that conveniently ilt within the central chamber of the enlarged plug portion 9. The core II of the magnet cooperates with the armature I8 fixed centrally on the diaphragm I9 and is operated ther- 35 mostatically, as will be presently explained. Said diaphragm is fastened to the arms of the yoke by screws 20 or other effective means.

A suitable thermostat comprises one'or more bi-metallic strips 2| secured at one end to a binding post 22 and at its free end carrying a contact 23 that coacts with a similar and fixed contact 25 on the post 24. Thus when the thermostat strips 2| are subjected to high temperature they 45 contract and bring the contacts 23 and 24 together closing a circuit through the winding of the magnet, and in turn energizing and vibrating the armature of the diaphragm. The two contact points are normally separated at such .dis- 50 tance as to cause the contact to close when the Vtemperature has risen to one hundred thirty (130) degrees Fahrenheit; or, if preferred, at any other predetermined temperature. It is obvious the farther the contact points are set apart the forth by providing more than two lai-metallic bars and cooperating contacts, if desired, said devices being arranged compactly around the magnet winding, preferably symmetrically spaced from one another so as to face in different directions when the device is in use.

A suitably designed casing 26 encloses the working parts of the device as shown in Figure 1. The flange portion 21 of said casing overlies the plug part 9 and by suitable indentures is securely held in position by engagement with the heads of screws 20.

It is to be understood the invention as here disclosed is not limited to the details of construction shown and described, as these may be varied widely Without departing from the spirit of the invention as dened by the claims.

What is claimed as new is:

1. A unitary lire-alarm device adapted to be plugged into the socket terminal of a standard lighting system, comprising a plug of insulating material having an open chamber at one end and two terminal contacts at least one of which is at its opposite end, an annular ring of insulating material at the chambered end of the plug, a substantially U-shaped bracket extending across said chambered portion of the plug and the legs of which project outwardly therefrom, the inter-r mediate portion of the bracket contacting with the outer face of said insulating ring, an electromagnet and means to secure the same to the bracket between its legs, a diaphragm secured to the legs of the bracket and having an intermediate portion thereof overlying the core oi' the l the thermostatic switch, and the other plug contact in series circuit.

2. A self-contained nre-alarm unit adapted to be plugged into a standard lighting or similar socket, comprising a plug of insulating material carrying two electrical contacts at least one of which is at an end of the plug, a yoke extending across the other end of the plug with the legs of the yoke extending therefrom, means for connecting the yoke with the plug, a ring of insulating material interposed between the yoke and a face of the plug, an electro-magnet located between the legs of the yoke, means for attaching the same to the yoke, a diaphragm having a portion thereof closely overlying the core of the magnet, means for attaching the diaphragm to the legs of the yoke, a thermostatic switch supported from the said ring of insulating material, and means connecting one plug contact, the electro-magnet, the thermostatic switch, and the other contact in series circuit.

3. A self-contained fire-alarm unit adapted to be plugged into a standard lighting or similar socket, comprising a plug member of insulating material having a chambered portion at one end and two electrical contacts at least one of which is at its other end, a yoke having a portion extending across the chambered end of the plug with the legs of the yoke projecting outwardly, means connecting the yoke with the plug, an electromagnet and means for attaching the same between the legs of the yoke, a flanged diaphragm having a portion thereof lying parallel with the core of the magnet and the flange of which engages the legs of the yoke, a thermostatic switch 5 and means connecting one plug contact, the electro-magnet, said switch and the other contact in series circuit, headed screws passing thru the flange of the diaphragm and entering the legs of the yoke, a dome-shaped casing enclosing the 10 mechanism of the unit, said casing having an opening in its dome thru which a portion of the plug terminal projects, and the lower portion of the casing having seats positioned to receive the aforesaid headed screws, and means for support-1 15 ing the thermostatic switchy from the plug.

4. A unitary fire-alarm device adapted to be plugged into the socket terminal of a standard lighting system, comprising a plug of insulating material having two contacts atleast one of 20 which is at one end of the plug and the other end of the plug shaped to form an open chamber,

a U-shaped yoke having its blght portion crossing the said open end of the chamber, with the legs of the yoke projecting away from the plug, 25 an electro-magnet located between the legs of the yoke, a diaphragm arranged parallel to the said vblght portion of the yoke, an armature car ried by the diaphragm opposite the electromagnet core, a thermostatic switch supported 30 from the plug, means connecting one plug contact, the electro-magnet, the thermostatic switch and the other plug contact in series circuit, and means for supporting the yoke from the plug and thleg electro-magnet and diaphragm from the yo e.

5. A unitary tire-alarm device adapted to be plugged into the socket terminal of a standard lighting system, comprising a plug of insulating material having an open chamber at one end and two terminal contacts, a yoke-shaped bracket having a portion extending across said chambered portion of the plug and the legs oi' which project outwardly therefrom, means for attaching the bracket to the plug, an electro-magnet located between the legs of the bracket and means for attaching the same thereto, a diaphragm and means forattaching the same to the legs of the bracket and having an intermediate portion overlying the core of the magnet, a thermostatic switch, and means for supporting the same from the plug, and means connecting one plug contact, the electro-magnet, the thermostatic switch, and the other plug contact in series circuit.

6. A unitary nre-alarm device adapted to be plugged into the socket terminal of a standard lighting system, comprising a plug of insulating material having an enlarged chambered portion at one end and a reduced portion carrying two terminal contacts at least one of which is at the end of the reduced portion, a substantially U-shaped yoke extending across said chambered portion of the plug and the legs of which project outwardly therefrom, means for attaching the 65' yoke to the plug, an electro-magnet located between the legs of the yoke and means for attaching the same thereto, a diaphragm having an intermediate portion overlying the core of the magnet, means for attaching the diaphragm v to the legs of the yoke, a bi-metal thermostatic switch of arched formation arranged substantially concentric with the electro-magnet, means for supporting the switch from the plug and means connecting one plug contact, the electro- 74s magnet, the thermostatic switch and the other plug contact in series circuit.

'1. A unitary ilre alarm device adapted to be plugged into the socket terminal of a standard lighting system, comprising a plug ci' insulating material having an enlarged chambered portion at'one end and a reduced portion at the other end, said reduced portion including a cap piece, a bolt securing the cap piece in position and a threaded sleeve en'closing the reduced portion, said bolt and threaded sleeve constituting two terminal contacts, a yoke-shaped bracket having a portion extending across Athe enlarged chambered portion of the plug and the legs of which project outwardly therefrom, means for attaching the bracket to the plug, an electro-magnet, and means for attaching the same to and between the legs of the bracket, a diaphragm having an intermediate portion overlying the core of the magnet and means for securing the same to the bracket, a bi-metallic thermostatic switch supported from the plug, means connecting one plug contact, the electro-magnet, the thermostatic switch, and the other plug contact in series circuit, and a removable dome-shaped casing having an opening through which the reduced portion oi' the plug projects, said dome surrounding the other parts of the alarm mechanism.

8. A self-contained alarm unit comprising a terminal plug adapted to be cooperatively associated with a conventional lamp socket of a standard lighting system, said plug including two contact members terminating adjacent one end of the plug and means for insulating them from each other, a signal device supported by said plug by a bracket extending from the other end oi' said plug and including an electro-magnet having its core arranged co-axially with the plug and a vibratory diaphragmextending across the pole of said magnet and supported at its periphery by said bracket, a thermally-operated switch responsive to a pre-determined ambient temperature to operate the signal device, and including a fixed contact and a bi-metal blade arched about the electro-magnet, an annulus of insulating material supported from the plug and means for attaching the bi-metal blade and the fixed contact thereto, and means connecting one plug contact, said signal device, said thermally operated switch, and the other plug contact in series circuit.

9. A self-contained fire alarm unit, comprising a terminal plug adapted to be plugged into the socket terminal of a standard lighting system, said plug composed of insulating material carrying two electrical contacts at least one of which is at one end of the plug, an alarm mechanism, means for attaching the same to that end of the plug opposite the end carrying the said contact and including an electrically-operated vibratory diaphragm, a thermostatic switch and means connecting one plug contact, the electri-` cally-operated alarm mechanism, the thermostatic switch and the other plug contact in series circuit.

10. A self-contained nre alarm unit, comprising a terminal plug adapted to be plugged into the socket terminal of a standard lighting system, said plug composed of insulating material and carrying two contacts at least one of which is at one end of the plug, alarm mechanism and means for attaching the same to that end of the plug opposite the contact-carrying end thereof including a support, means for securing the same to the plug terminal, an electro-magnet and means for attaching the same to the support, a vibratory diaphragm having an intermediate portion thereof overlying the pole of the electromagnet, and a thermostatic switch, said diaphragm and thermostatic switch being supported by said plug, and means connecting one 'plug contact, the electro-magnet, the thermostatic switch and the other plug contact in series circuit.

1l.. A self-contained iire alarm unit, comprising a plug terminal adapted to be plugged into the socket terminal of a standard lighting system, said plug composed of insulating material and carrying two contacts at least one of which is at one end of the plug, alarm mechanism and means for attaching the same to that end of the plug opposite the contact-carrying end thereof including a support, an electro-magnet and means' for attaching to the support, a vibratory diaphragm having an intermediate portion thereof overlying the pole of the electro-magnet, a thermostatic switch, said diaphragm and switch being supported by said plug, means connecting one'plug contact, the electro-magnet, the thermostatlc switch, and the other piug contact in series circuit, and a dome-shaped casing having an opening in its dome thrue which an end oi' the terminal plug projects and means for releasably securing the casing to the plug.

l2. A self-contained alarm unit, comprising a terminal plug adapted to be cooperatively associated with a conventional lamp socket of a standard lighting system, said plug composed of insulating material and carrying two contacts at least one of which is at an end of the plug, an

alarm mechanism and means securing the same to the other end of the plug, said mechanism including an electrically-operated sounding device, a bi-metallic thermally-iniiuenced contactmaking and breaking device, and means connecting one plug contact. the electrically-operated sounding device, the thermallyv iniiuenced contact-making and breaking device, and the other plug contact in series circuit.

13. A self-contained fire alarm unit, comprising a plug terminal adapted to be plugged into the socket terminal of a standard lighting system, said plug composed of insulating material and carrying two contacts, alarm mechanism and means for attaching vthe same to the plug and including a bracket secured to the end of the plug terminal opposite the contact-carrying portion thereof, a magnet coil carried by the bracket, a vibratory diaphragm also carried by the bracket and having an intermediate portion thereof overlying the pole of the magnet coil, a thermostatic switch of arched formation partially surrounding the magnet coil and supported by said bracket, and means connecting one plug contact, the electro-magnet, the thermostatic switch, and the other plug contact in series circuit.

14. A self-contained ilre alarm unit, comprising a terminal plug adapted to be plugged into the socket terminal of a standard lighting system, said plug composed of insulating material and carrying two contacts at least one of which is at an end of the plug, alarm mechanism and means for attaching the same to that end of the plug opposite the contact carrying portion said means including a yoke-shaped member having an intermediate portion extending across the lastmentioned end oi' the plug, an electro-magnet carried by the said member and having its coil located between the arms thereof, a vibratory diaphragm and means vfor attaching the same to 4 the arms ot the said yoke'member, said diaphragmhavinganintermediateportionthereof overlying the pole of the magnet. a bi-metallio@ thermoetatic switch supported by said bracket and partially surrounding the magnet, and means connecting one plug contact, the electro-magnet, the thermostatic switch, and the other plug con tact in series circuit.

15. A self-contained iire alarm unit, comprising a terminal plug adapted to be plugged into the socket terminal of a standard lighting system, said plug composed of insulating material and carrying a pair oi' contacts at least o ne oi which is at one end oi' the plug, alarm mechanism and means for attaching the same to that end o! the plug opposite the end carrying said contacts* and including a bracket attached to the plug,ra yoke member mounted on the bracket and extending transversely across an end thereof, a diaphragm mounted on the arms of the yoke member, an electro-magnet located between the arms oi' the yoke and the diaphragm, with an intermediate portion of the diaphragm overlying the pole of the magnet, an arched bi-metallic thermostatic switch partially surrounding the magnet, saidA magnet and the thermostatic switch being supported by said bracket, and means connecting one plug contact, the electro-magnet. the theracoaeso l L,

and the other plug contact in series circuit. l5'

17,. A self-contained alarm unit comprising a terminal plug adapted to be cooperatively alociated with a conventional lamp socket ot a standard lighting system, said plug including two contact members and .means for insulating them 20 from each other, a signal device supported` by said P1118, a thermally operated switch responsive to a predetermined ambient temperature to-operate the signal device supported from saidpiug and means connecting one.plug contact, said25 I signal device said thermally operated switch and the other plug contact in series circuit.

GEORGE HOWIEII DAVIS. 

